. Annual report. 1st-12th, 1867-1878. Geology. VACKARD.] MORPHOLOGY OF 371. XIV, fig". 4). The body-avails are rather thick and the muscles are well de- veloped, particularly the dorsal extensor muscles, and the motor or exten- sor muscles of the limbs, which arise in part from the dorsal re- gion, and in part from the sides and sternal region. The body cavity is rather small. The heart is large, either cylindrical as iu Estheria, or flattened as in Tham- nocephalus. The digestive tract is large, capacious, and the cav- ity of the head is mainly filled with the two liver mass
. Annual report. 1st-12th, 1867-1878. Geology. VACKARD.] MORPHOLOGY OF 371. XIV, fig". 4). The body-avails are rather thick and the muscles are well de- veloped, particularly the dorsal extensor muscles, and the motor or exten- sor muscles of the limbs, which arise in part from the dorsal re- gion, and in part from the sides and sternal region. The body cavity is rather small. The heart is large, either cylindrical as iu Estheria, or flattened as in Tham- nocephalus. The digestive tract is large, capacious, and the cav- ity of the head is mainly filled with the two liver masses; the brain being remarkably small, while the nervous cord, especially the brain and succeeding gan- glia, are remarkably small and weak, compared with other Crus- tacea, either the malacostracous or the entomostracous orders; this peculiarity is Well brought Fig. 25.—Section of A pus. ht, heart; int, intestine; nnf in tIia rrmiRTTArsp «jprinn<a ng, ganglion.; c, carapace; 1-6, the six exites, 1 being out in me trans% crse _ sections, tj* gnat-hobase: gill aild/b< flabelhuu, representing the where the diminutive size 01 the exites. thoracic ganglia, particularly in Estheria (Plate XXIV, figs. 9w, 9), is noteworthy. The apparent bulk of the body is largely due to the large size and nature of the leaf like or foliaceous appendages, with their broad attachments; the latter peculiarity is characteristic of the Branch- iopods in general and the Phyllopods especially, and is quite different from the definite, small coxal articulations of the legs of Malacostraca or Copepoda. The ovaries or testes, according to the sex, form a large lobulated mass extending along each side of the digestive canal, as far forward as the base of the head. Their relations in Apns are seen in Plate XXXII, fig. 2, and in Thamnocephalus in Plate XIV, fig. 4. Nomenclature of the body-regions and appendages.—As the terms "head," "thorax," and " abdomen " are more or l
Size: 1576px × 1586px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1860, bookpublishe, booksubjectgeology
